Alternate channel for carrying selected message types

ABSTRACT

A method is implemented by a subscriber unit in a wireless communication for establishing a network session. The subscriber unit encodes an acknowledgment message for transmission on a shared reverse link channel to a base station. Acknowledgment information associated with a received session tag at the subscriber unit to the base station is transmitted over the shared reverse link channel, on a condition that the session tag is received from a network server via the base station on a forward link channel and identified by the subscriber unit. The acknowledgment is transmitted on a reverse traffic channel on a condition that the session ID tag is not identified by the subscriber unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/572,313, filed Aug. 10, 2012, which is a continuation of U.S. patentapplication Ser. No. 12/400,872, filed Mar. 10, 2009, now U.S. Pat. No.8,274,954, issued Sep. 25, 2012, and is a continuation of U.S. patentapplication Ser. No. 11/235,725, filed Sep. 26, 2005, now U.S. Pat. No.7,502,351, issued Mar. 10, 2009, and is a continuation of U.S. patentapplication Ser. No. 09/775,304, filed Feb. 1, 2001, now U.S. Pat. No.6,954,448, issued Oct. 11, 2005, which are incorporated by reference asif fully set forth.

BACKGROUND OF THE INVENTION

Network systems that provide reliable delivery of information typicallyuse some form of acknowledgments (ACKs) or negative acknowledgments(NAKs) to notify a sender that data transmitted from a source isproperly received at a target device. For instance, the TCP/IP (TransferControl Protocol/Internet Protocol) supports bi-directional data messagetraffic where feedback messages in a reverse direction of a data blocktransmission indicate whether or not the block of data is properlyreceived at a target device.

Most packet-switched systems in which digital information is transmittedover a wireless, bi-directional link attempt to improve efficiency andmaximize capacity by allocating bandwidth on an as-needed basis. Thatis, a reverse direction traffic channel for carrying acknowledgmentmessages as previously discussed is allocated for use only when suchmessages become available for transmission to a source in response tothe reception of data at a target device. In these systems, bandwidthmust be allocated and deallocated dynamically so that wireless resourcesfor transmitting ACK messages are not dedicated when no ACK messages arebeing transmitted. This process of allocating and de-allocating trafficchannels for the transmission of these sporadically generated ACKmessages is cumbersome due to substantial overhead processing requiredto allocate and deallocate channels to multiple subscriber unitscompeting for their use. In this instance, wireless resources are wastedto the extent that channels cannot be utilized in a reverse link until aconfirmation is received from a subscriber unit that a channel isproperly assigned. Thus, there can be a substantial delay between thetime a subscriber wishes to transmit and the time it is able to do so.

Rather than assigning channels on an as-needed basis, a wholly dedicatedwireless channel in a reverse direction can be allocated for use by aparticular subscriber unit to support the transmission of sporadicallygenerated messages. However, the continuous allocation of an entirechannel for such messages is often a waste of resources, especially whenmultiple users are competing for their use and the channel is capable ofcarrying much more traffic than merely occasional messages.

SUMMARY OF THE INVENTION

The present invention is generally directed towards a method and systemfor enhancing the utilization of resources in a wireless communicationsystem. In an illustrative embodiment, a shared channel is allocated tocarry selected messages from each of multiple subscriber units to a basestation. These selected messages as generated by a subscriber unit,which can otherwise be transmitted over an assigned reverse link trafficchannel, are instead encoded and transmitted to the base station over ashared reverse link channel. Preferably, the shared reverse link channelis time-slotted and each subscriber unit transmits information to thebase station in an assigned time slot so that the base station receivingthe selected messages can identify from which subscriber unit a messageis sent.

The shared channel is optionally structured so that bits in a time slothave a specified meaning. More specifically, certain bits in a time slotof the shared channel as transmitted by a subscriber unit are used tocommunicate a particular message to the base station. For instance, asingle bit itself can be used to transmit a message, where the settingof the bit in the time slot indicates a message-type. In an applicationwhere the single bit is an ACK/NAK bit (Acknowledgment/No Acknowledgmentbit), a logic one can indicate that a message is an “acknowledgment”message while a logic zero can indicate that a message is a “noacknowledgment” message. Thus, a base station transmitting informationover a forward link channel to a subscriber unit can be providedfeedback via reverse link messages transmitted in a shared channel toindicate whether the forward link messages are appropriately received atthe subscriber unit.

In an application where messages are not transmitted in every frame,i.e., an acknowledgment message is not sent to the base station everyperiodically repeating time slot from a subscriber unit, a complementarydata valid bit can be used to indicate that the setting of other bits,such as the ACK/NAK bit as previously described, are meaningless. Inthis way, two bits can be used to communicate a message to the basestation. More specifically, a complementary data valid bit can be set asa logic one to indicate that the ACK/NAK bit is valid while the ACK/NAKbit itself can be used to identify the type of acknowledgment message aspreviously discussed. Alternatively, the complementary data valid bitcan be set as a logic zero to indicate that the setting of the ACK/NAKbit is meaningless and that no message is being sent. It is thereforepossible for an assigned subscriber unit not to transmit a message tothe base station for every successive and periodically repeating timeslot of the shared channel.

According to this method, a message that would otherwise be transmittedalong with other data payload messages on a reverse link traffic channelto the base station can be converted into a substitute message that isencoded as one or two bits of information in a time slot of the sharedreverse link channel. A selected message type can therefore betransmitted to a target device using fewer bits than would otherwise benecessary if the same message was transmitted over a communication linkalong with a set of random data packets that must be decoded todetermine their content. Another advantage of the methods according tothe principles of the present invention is that a processing unitreceiving a reverse link message in a time slot can identify acorresponding message-type in less time since it is not necessary toprocess multiple layers of a data packet to determine its contents.Rather, the bit settings within a time slot of a monitored sharedchannel can be decoded to determine a message-type, where the time-slotsthemselves indicate from which of multiple field units the messagepertains.

Another aspect of the present invention involves supporting multipletypes of network messages in a given time-slot of the shared reverselink channel. For example, the time slotted channel can include multipleacknowledgment messages, each of which is generated at different networklayers. The time-slotted channel also can be structured to supportmultiple message-types other than acknowledgment messages.

Yet another aspect of the present invention involves providingadditional bit information to define other attributes of a message. Forexample, certain bits of a message can be used to identify a layer 2frame number indicating which of multiple FEC frames of a data payloadtransmitted over a forward link channel is being acknowledged by areceiving subscriber unit in a time-slot of the reverse link channel.Preferably, the layer 2 frame number is encoded in a time slot as a3-bit sequence indicating the frame number of the FEC frame received ornot received at a corresponding subscriber unit. According to thismethod of acknowledging properly or improperly received frames at asubscriber unit, the base station can be notified which if any framesmust be re-transmitted.

Layer 3 ACK/NAK messages as transmitted over the reverse link caninclude multiple bits to identify a particular superframe that is beingacknowledged as a result of data transmissions over a forward linkchannel. A superframe is a block of data such as a TCP/IP (TransferControl Protocol/Internet Protocol) data packet that is typicallyreduced in size before transmission over multiple frames of the forwardlink channel. The process of transmitting a data block to a targetsubscriber unit first involves receiving a block of data such as an IP(Internet Protocol) network packet at the base station. Prior totransmission over the wireless link, the network packet is preferablysubdivided into multiple segments. These segments are then transmittedto a subscriber unit over multiple frames of the forward link channel.Segments received at a subscriber unit are then reassembled toreconstruct the original IP packet or superframe. This recaptured datablock or superframe is then forwarded to, for example, a target PCdevice coupled to the subscriber unit. Meanwhile, an acknowledgmentmessage is generated at the subscriber unit indicating whether theentire superframe is received at the subscriber unit. Preferably, thislayer 3 acknowledgment message transmitted in time slot of the sharedreverse link channel includes a bit sequence indicating which particularsuperframe is being acknowledged. More specifically, a time slot caninclude indicator bits identifying whether a layer 3 message is an ACKor NAK. A time slot can further include encoded bits indicating theparticular number of the superframe to which the acknowledgment messagepertains.

The principles of the present invention can also be used to supportlayer 4 acknowledgment messages. Layer 4 acknowledgment messages aregenerated by a PC device coupled to the subscriber unit. Theseacknowledgment messages are transmitted in a reverse direction to thebase station to indicate a reception of a data block such as a TCP/IPnetwork packet or superframe transmitted to the subscriber unit over theforward link. Rather than transmit a layer 4 acknowledgment networkpacket over a reverse link traffic channel in its original, form as donewith forward link data transmissions, the subscriber unit creates asubstitute message that is transmitted in a corresponding time slot overthe shared reverse link channel. This involves identifying a layer 4acknowledgment message at the subscriber unit and encoding it in a bitsequence of a time slot so that the base station upon receipt canreconstruct meaningful aspects of the message as originally generated bythe PC device.

In this way, a network message generated by a PC device is interceptedat a subscriber unit and is encoded as a substitute message that istransmitted in a time slot to the base station. The base station thendecodes the message received in the time slot and reconstructs theoriginal or substantially similar network message. After the substitutemessage as received in a time slot is reconstructed into an original orsubstantially similar network packet at the base station, the networkmessage is forwarded to the appropriate target device on, for example, awired network in communication with the base station.

One application of the inventive shared channel is a reverse link of aCDMA (Code Division Multiple Access) communication system. In such asystem, data blocks of network packets corresponding to a particularconnection between a client and server are presented to a base stationtransmitter where they are repackaged into manageably sized sub-packetsfor transmission to a particular subscriber unit over a wireless link.As previously discussed, a shared time-slotted reverse link channel isused to carry selected message-types that would otherwise be transmittedalong with a data payload over an assigned reverse link traffic channel.For example, ACK and NAK messages pertaining to one of multiple TCP/IPnetwork sessions of corresponding subscriber units could otherwise betransmitted over multiple dedicated reverse link channels on anas-needed basis. However, according to the principles of the presentinvention, the messages are instead transmitted over the shared channel.

In a preferred embodiment, time-slots are implicitly assigned for use bysubscriber units based on the allocation of forward link channels. Forexample, a subscriber unit is optionally allocated use of a time slot inthe shared reverse link depending on which traffic channels areallocated in the forward link to transmit a data payload to thesubscriber unit. More specifically, if the base station transmitsforward link messages such as a data payload on traffic channel #1, timeslot #1 of the shared reverse link channel is implicitly assigned foruse by that particular subscriber unit to transmit feedback informationin a reverse link path. Use of a particular time slot by a newlyassigned subscriber unit is preferably delayed so that the subscriberunit can receive and process data received on the newly assigned forwardlink channel and respond appropriately in the reverse link time slot.

In an alternate embodiment, one or multiple time slots are explicitlyassigned for use by a subscriber unit via a corresponding message senton a forward link channel from the base station to a correspondingsubscriber unit.

Notably, a subscriber unit can receive data information from the basestation on multiple forward link traffic channels while providingcorresponding feedback messages on multiple implicitly assigned timeslots of the shared reverse link channel.

If no forward link channels are assigned for use by a particular fieldunit and no time slots are available for allocation in the sharedreverse link channel, information can be transmitted from the field unitto the base station via the assignment of reverse link traffic channels.

As previously discussed, the shared channel can be structured to encodenetwork messages generated at multiple layers. Alternately, the sharedchannel can be an unstructured channel partitioned into time slots thatcarry generic payload data. For example, a network message or raw datacan be encoded in a time slot of the shared channel where a receiverdevice must decode a data payload to determine a message type. Thus, theshared channel can carry any type of message and not just acknowledgmentor feedback messages. For instance, a data payload transmitted in a timeslot of the shared channel can be a maintenance message to support acorresponding link between the field unit and base station. Otherwise,such data can be transmitted over a traffic channel.

Another aspect of the present invention involves allocating additionalbandwidth such as a reverse link traffic channel for transmitting a datamessage to the base station when throughput capacity afforded by anassigned time slot is exceeded. That is, if a field unit must transmitmore information to the base station than is possible via an assignedtime slot, at least part of a reverse link traffic channel isadditionally assigned for use by the field to transmit information tothe base station.

Preferably, a shared reverse link time-slotted feedback channel repeatson a periodic basis so that feedback is provided on a discrete butcontinuous basis to the base station when a time slot is assigned to asubscriber unit. Thus, minimal resources can be used to transmitfeedback or other types of messages in a reverse link direction of thewireless communication system. This aspect of the present invention isparticularly advantageous in applications where a large data block suchas web page information is transmitted from the base station to asubscriber unit and it is necessary to support at least a minimalcommunication in the reverse direction back to the base station.

Multiple subscriber units compete for the use of wireless channelresources in most wireless communication systems. As previouslydiscussed, there is often high demand for data throughput on the forwardlink channel to carry data payloads such as web page information toremotely located subscriber units. To support high throughput of data,multiple traffic channels are allocated on an as-needed basis to supportsuch data transfers on the forward link to the subscriber unit. In thisapplication, sporadically generated ACK and NAK messages are transmittedin a reverse link from the subscriber unit to the base station.According to this aspect of the present invention as discussed, reverselink messages are encoded as substitute messages that are transmittedover a time-slotted reverse link channel. This reduces the overheadassociated with the allocation of a whole a reverse link traffic channelto a corresponding subscriber unit every time a sporadic ACK or NAKmessage must be transmitted to the base station.

Alternatively, a portion of a time-slotted reverse-link traffic channelcan be assigned on a continuous basis to a subscriber unit fortransmitting occasional messages to the base station.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIG. 1 is a block diagram illustrating a joint acknowledgment channel ina wireless communication system according to the principles of thepresent invention.

FIG. 2 is a detailed block diagram of a transmitter and receiver circuitfor communicating data over a wireless link according to the principlesof the present invention.

FIG. 3 is a timing diagram of a time-slotted joint acknowledgmentchannel according to the principles of the present invention.

FIG. 4 is a timing diagram illustrating processing delays associatedwith the transmission of messages in a time slot of the jointacknowledgment channel according to the principles of the presentinvention.

FIG. 5 is a table for tracking time slot assignments of a jointacknowledgment channel according to the principles of the presentinvention.

FIG. 6 is a table for tracking individually established communicationsessions according to the principles of the present invention.

FIG. 7 is a block diagram illustrating how a feedback message at asubscriber unit is transmitted in a time slot of the jointacknowledgment channel, reformatted at a base station and furtherforwarded over a wired network to a target address according to theprinciples of the present invention.

FIG. 8 is a flow chart illustrating the assignment of time slot usage ofa joint acknowledgment channel according to the principles of thepresent invention.

FIG. 9 is a flow chart illustrating how acknowledgment messagestransmitted in a time slot of the joint acknowledgment channel areprocessed at a base station according to the principles of the presentinvention.

FIG. 10 is a flow chart illustrating how a time slot of the jointacknowledgment channel is processed according to the principles of thepresent invention.

FIG. 11 is a flow chart illustrating how sessions are tracked for layer4 message processing according to the principles of the presentinvention.

FIG. 12 is a flow chart illustrating how acknowledgment messages areprocessed according to the principles of the present invention.

FIG. 13 is a flow chart illustrating how acknowledgment messages areprocessed at a subscriber unit according to the principles of thepresent invention.

FIG. 14 is a flow chart illustrating how time slot usage of the jointacknowledgment is tracked at a subscriber unit according to theprinciples of the present invention.

FIG. 15 is a flow chart illustrating how layer 2 acknowledgment messagesare generated at a subscriber unit according to the principles of thepresent invention.

FIG. 16 is a flow chart illustrating how layer 3 acknowledgment messagesare generated at a subscriber unit according to the principles of thepresent invention.

FIG. 17 is a flow chart illustrating how layer 4 acknowledgment messagesare generated at a subscriber unit according to the principles of thepresent invention.

FIG. 18 is a flow chart illustrating how a layer 4 acknowledgmentmessage is generated and transmitted in a jack channel time slotaccording to the principles of the present invention.

FIG. 19 is a flow chart illustrating how a layer 4 ACK message receivedin a time slot of the channel is processed at a base station accordingto the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A description of preferred embodiments of the invention follows.

FIG. 1 is a block diagram illustrating a communication system supportingthe transmission of data information over multiple allocated wirelesscommunication channels. As in many wireless communication systems, userscompete for wireless bandwidth allocation. Hence, it is desirable thatthe wireless communication 10 is optimized for data throughput and, incertain applications, hi-speed bursts of data throughput.

Certain aspects of the present invention are based on the recognitionthat some messages transmitted over a wireless link are redundant to theextent that specific protocols are repeatedly used to communicate datainformation between a base station and each of multiple subscriberunits. For example, one aspect of most network protocols involvestransmitting acknowledgment messages in a return communication path toindicate the status of transmitted and received data between networkdevices such as a server and a client. This type of feedback in areverse communication path ensures that messages are properly receivedat a target device, increasing overall link quality between atransmitter and receiver device.

Consider packet-switched systems such as those based on TCP/IP (TransferControl Protocol/Internet Protocol). During a typical networkcommunication session, acknowledgment and similar types of linkmaintenance messages are repeatedly generated as encoded data packetsthat are transmitted as network messages along with corresponding datainformation messages that are used at an application layer of a networksession. Considerable processing power at a target device is oftennecessary to quickly distinguish link maintenance messages from actualdata payload messages. It is preferred that processing time of a messageat an intermediate routing device is minimized so that the message canbe transmitted to a corresponding target in as little time possible.

According to one aspect of the present invention, messages transmittedover a wireless link from a subscriber unit 14 are analyzed to determinetheir content prior to transmission. Selected messages of a particulartype are intercepted and encoded for transmission over a structuredchannel to a target device in lieu of being transmitted as a random datapacket that must be analyzed at multiple layers to determine itscontent. In a specific application, the structured channel can beadapted to transmit common message types such as acknowledgment messagesindicating whether data information is properly received and decoded ata target device such as a server.

According to the following description, communication system 10 isdescribed as a wireless communication link such as a CDMA radio channelutilizing shared channel resources. However, it should be noted that thetechniques described herein can be applied in other applicationssupporting shared access. For example, the principles of the presentinvention can be applied to other types of media such as telephoneconnections, computer network connections, cable connections, or otherphysical media to which allocation of resources such as data channelsare granted on an as-needed basis.

As shown, communication system 10 includes a number of Personal Computer(PC) devices 12-1, 12-2, . . . 12-h, . . . 12-m, correspondingsubscriber units or terminals 14-1, 14-2, . . . 14-h, . . . 14-m, andassociated directional antenna devices 16-1, 16-2, . . . 16-h, . . .16-m. Centrally located equipment includes a base station antenna 18,and a corresponding base station 20 that includes high speed processingcapability.

Base station 20 provides connections to and from a network gateway 22,network 24 such as the Internet, and network file server 30.Communication system 10 is preferably a demand access, point tomulti-point wireless communication system such that the PC devices 12can transmit data to and receive data from network server 30 throughbi-directional wireless connections implemented over forward links 40and reverse links 50. That is, in the point to multi-point multipleaccess wireless communication system 10 as shown, a given base station20 typically supports communication with a number of differentsubscriber units 14 in a manner which is similar to a cellular telephonecommunication network. Accordingly, system 10 can provide a frameworkfor a CDMA wireless communication system where digital information isrelayed on-demand between multiple mobile cellular users and a hardwirednetwork 24 such as the Internet.

PC devices 12 are typically laptop computers, handheld units,Internet-enabled cellular telephones, Personal Digital Assistant(PDA)-type computers, digital processors or other end user devices,although almost any type of processing device can be used in place of PCdevices 12. One or multiple PC devices 12 are each connected to arespective subscriber unit 14 through a suitable wired connection suchas an Ethernet-type connection via cable 13.

Each subscriber unit 14 permits its associated PC device 12 access tothe network file server 30. In the reverse link 50 direction, that is,for data traffic transmitted from the PC 12 towards the server 30, thePC device 12 transmits an Internet Protocol (IP) level network packet tothe subscriber unit 14. The subscriber unit 14 then encapsulates thewired framing, i.e., Ethernet framing, with appropriate wirelessconnection framing so that data packets can be transmitted over thewireless link of communication system 10. Based on a selected wirelessprotocol, the appropriately formatted wireless data packet then travelsover one of the radio channels that comprise the reverse link 50 throughsubscriber unit antenna 16 to base station antenna 18. At the centralbase station location, the base station 20 then extracts the radio linkframed data packets and reformats the packets into an IP format. Thepackets are then routed through gateway 22 and any number or type ofnetworks 24 to an ultimate destination such as a network file server 30.In one application, information generated by PC device 12 is based on aTCP/IP protocol. Consequently, a PC device 12 has access to digitalinformation such as web pages available on the Internet. It should benoted that other types of digital information can be transmitted overchannels of communication system 10 based on the principles of thepresent invention.

Data can also be transmitted from the network file server 30 to the PCs12 on a forward link 40. In this instance, network data such as anInternet Protocol (IP) packets originating at the file server 30 travelon the network 24 through the gateway 22 to eventually arrive at thebase station 20. As previously discussed for reverse link datatransmissions, appropriate wireless protocol framing is then added toraw data such as IP packets for communication of the packets over awireless forward link 40. The newly framed packets then travel throughthe antenna 18 and 16 to the intended receiver subscriber unit 14. Anappropriate target receiver subscriber unit 14 decodes the wirelesspacket protocol layer, and forwards the packet or data packets to theintended PC device 12 that performs IP layer processing.

A given PC device 12 and file server 30 can therefore be viewed as theend points of a duplex connection at the IP level. Once a connection isestablished between the base station processor 20 and correspondingsubscriber unit 14, a user at the PC device 12 can then transmit data toand receive data from the file server 30 on an as-needed basis.

Reverse link 50 optionally includes different types of logical and/orphysical radio channels such as a JACK (Joint Acknowledgment) channel54, an access channel 51, multiple traffic channels 52-1, . . . 52-m,and a maintenance channel 53. The reverse link access channel 51 is usedby the subscriber units 14 to request use of traffic channels by thebase station 20. For example, traffic channels carrying data packets canbe assigned to a user on an as-needed basis. The assigned trafficchannels 52 in the reverse link 50 then carry payload data from thesubscriber unit 14 to the base station 20. Notably, a given link betweenthe base station 20 and subscriber unit 14 can have more than onetraffic channel 52 assigned to it.

Maintenance channel 53 carries maintenance information such assynchronization and power control messages to further supporttransmission of digital information over both the reverse link 50 andforward link 40.

JACK channel 54 is a shared and structured reverse link channel fortransmitting messages from a subscriber unit 14 to the base station 20.Preferably, the JACK channel 54 is partitioned into time slots of equalduration and is structured to have a specified bit mapping. According tohow the bits in a time slot are set by an assigned subscriber unit 14,the subscriber unit 14 communicates messages to the base station. Thisaspect of the present invention is described in more detail later in thespecification.

The forward link 40 can also include a paging channel 41, which is usedby the base station 20 to inform a subscriber unit 14 of generalinformation such as that one or multiple forward link traffic channels52 have been allocated to it for the transmission of data. Additionally,the channel is used to inform the subscriber unit 14 of allocatedtraffic channels 52 in the reverse link 50 direction. Traffic channels42-1 . . . 42-n on the forward link 40 are then used to carry payloadinformation from the base station 20 to a corresponding targetsubscriber unit 14.

Additionally, maintenance channels 43 carry synchronization and powercontrol information on the forward link 40 from the base stationprocessor 20 to the subscriber units 14.

The traffic channels 42 on the forward link 40 can be shared amongmultiple subscriber units 14 based on a Time Division Multiplexingscheme. Specifically, a forward link traffic channel 42 is optionallypartitioned into a predetermined number of periodically repeatingtime-stamped slots for transmission of data packets from the basestation 20 to multiple subscriber units 14. It should be understood thata given subscriber unit 14 can, at any instant in time, have multipletime slots or no time slots assigned to it. In certain applications, anentire time-slotted forward or reverse link traffic channel is assignedfor use to a particular subscriber unit 16.

FIG. 2 is a block diagram illustrating a combination of hardware andsoftware components for supporting a data block transfer over a wirelesslink according to the principles of the present invention. Although basestation 20 as shown includes details of a transmitting device andsubscriber unit 14 as shown includes details of a receiving device, boththe base station 20 and subscriber unit 14 include complementaryhardware and software as shown so that they can both transmit andreceive wireless data information.

One aspect of the present invention involves transmitting data block 205over a wireless link so that it can be reconstructed as recaptured datablock 255 at subscriber unit 14. As shown, data block 205 is presentedto base station manager 210 for transmission over wireless communicationsystem 10. In one application, data block 205 comprises digital datatransmitted by server 30 through network 24 and gateway 22 to basestation processor 20. This data block 205 is routed to base stationprocessor 20 for transmission to a target receiver subscriber unit 14 ofcommunication system 10.

As previously mentioned, data block 205 can be a block of TCP/IP datapackets encapsulating, for example, web page information bound for atarget receiver subscriber unit 14. It should be noted that portions ofdata block 205 can be transmitted over the data channels to a targetreceiver even though only a portion of the data block 205 is received atbase station processor 20. More specifically, parts of a data block canbe transmitted over the wireless channels as such data is received atbase station 20.

In some instances it is undesirable to transmit an entire data block ina serial manner over a single dedicated traffic channel. Such atechnique can be ineffective for transmitting data if the throughputrate of the traffic channel link is low and the block of data to betransmitted is very large. It is preferable to transmit relatively largeblocks of data in as little time possible while still making efficientuse of wireless communication system 10. Thus, multiple traffic channels42 are often allocated for use by a particular subscriber unit 14 forhigh-speed data transfers from the base station 20 to a targetsubscriber unit 14.

Data block 205 is preferably reduced into manageable chunks so that itcan be transmitted piecewise over multiple channels to a target receiversubscriber unit 14. If only a single limited-bandwidth wireless channelwere utilized for such a data transfer as mentioned, large data blocks205 might otherwise be slowed by a bottleneck of a single channel unableto support a high throughput.

Data block 205 is presented to framer 215 that optimally reduces thesize of data block 205 by dividing it into sub-packets or sub-blocks ofdata based on operating parameters of communication system 10. A numberof bytes in each frame is not of particular importance to the presentinvention since the optimal division of a data block 205 depends on manyparameters of communication system 10.

In any event, framed data is fed to forward error correction (FEC)encoder 220. The FEC encoder 220 adds bit information to the framed datato permit error detection at a target subscriber unit 14. Based onredundancy, the forward error correction encoding ensures that data isaccurately received at a target receiver subscriber unit 14. Any numberof FEC encoder types can be used such as BCH codes, Block codes, turbocodes, turbo product codes and the like.

An FEC encoded frame is then forwarded from FEC encoder 220 to a coversequence circuit 228 that applies a cover sequence, C.sub.i,corresponding to a traffic channel over which the data is to betransmitted. The cover sequence circuit comprises code generator 225 andmixer 222.

A cover sequence C.sub.i can be any suitable sequence. One class of suchsequences are long pseudo-random noise (PN) codes. In this instance, acover sequence is applied by modulo-2 multiplication of the coversequence C.sub.i with FEC encoded frame data. A cover sequence can alsobe other near-orthogonal sequences that scramble encoded data.Preferably, a cover sequence will scramble the data sufficiently andcause an FEC decoder to fail in the decoding process if an incorrectcover sequence is applied at a receiver other than a target subscriberunit 14. This ensures separation of traffic channels such as thosesupported in a code division multiple access (CDMA) communicationsystem.

The signal output from cover sequence circuit 228 is then fed tomodulator 230. A modulation type is impressed upon this signal atmodulator 230 as selected by base station manager 210. Modulation typescan be any suitable type such as BPSK (binary phase shift keying), QPSK(quadrature phase shift keying), 8-psk, up to n-psk. A type ofmodulation to be used in the transmission of a data packet 205 dependson operating parameters of the wireless communication system 10.

Modulated signals generated by modulator 230 are then fed to summercircuit 232. In addition to the modulated traffic channels as previouslydiscussed, a pilot channel 236 and paging channel 235 are fed to summercircuit 232. Similar hardware and software as that previously discussedfor the traffic channel can be used to generate signals for the pilotchannel 236, paging channel 235 and other forward link channels.

RF up/down converter 245 is then used to transmit the information overwireless channels via antenna 18. Accordingly, data information istransmitted over forward link 40 channels to one or multiple subscriberunits 14 of wireless communication system 10. More specifically,multiple traffic channels are 42 generated at base station 20 to carrysub-blocks of data block 205 to a target receiver subscriber unit 14.

It should be noted that components of base station 20 can be duplicatedin a subscriber unit 14 to support the generation of multiple traffic orpaging channels. More specifically, multiple traffic channels can begenerated at base station 20 to carry sub-blocks of data block 205 to atarget receiver subscriber unit 14.

Subscriber unit 14 of FIG. 2 includes a block diagram of components forreceiving data transmitted from base station 20. Antenna 16 receiveswireless signals that are processed by RF up/down converter 295.Multiple assigned traffic channels are monitored and decoded for datadirected to a corresponding subscriber unit 14.

Each subscriber unit 14 preferably includes a cover sequence circuit275, a demodulator 280, an FEC decoder 270, a re-framer 265 and asubscriber unit manager 260. This combination of components is used tomonitor, receive and decode data information as it is received on aparticular traffic channel.

As shown, cover sequence circuit 275 is used to identify datatransmissions having a particular cover sequence of a CDMA channel. Thesignal generated from cover sequence circuit 275 is then fed todemodulator 280 where it is demodulated according to a type ofmodulation used in transmission of the data information. FEC decoder 270is then used to verify that data information is properly receivedwithout errors based on a forward error correction code. Finally,re-framer 265 processes the received data for recapturing sub-blocks orraw data of original data block 205. Received sub-blocks are recombinedat access unit manager 260 to produce recaptured data block 255.Preferably, recaptured data 255 block is identical or near-identical tooriginal data block 205. In applications supporting the transfer of IPdata packets, the raw data of recaptured data block 255 is forwarded toa corresponding PC device 12. As mentioned, the format of thisinformation can be based on, for example the TCP/IP network protocol.

In a similar but reverse manner as previously described, messagesgenerated at a subscriber unit are transmitted at the base station,where they are demodulated, decoded and otherwise processed.

FIG. 3 is a JACK channel (Joint Acknowledgment channel) illustrating anexemplary bit mapping according to the principles of the presentinvention. Preferably, JACK channel 54 is a time-slotted channel forcarrying messages such as feedback messages to base station 20 over ashared reverse link 50 channel.

Because the link between a server 30 and PC 12 includes a wirelessforward link channel 40, there is a need in certain applications tosupport communications from the PC device 12 to server 30 over a reverselink channel 50. A portion or all of such communications are preferablysupported by JACK channel 54. It should be noted that JACK channel 54 isoptionally a minimal link supporting sporadic communications other thanfeedback messages or acknowledgment messages from a subscriber unit 14to base station 20. It also should be noted that one or multipletime-slotted channel such as JACK channel 54 can be established in aforward link 40 for data payload communication from a subscriber unit 14to base station 20. More specifically, the principles of the presentinventions are not limited to applications such as a reverse linkchannel of a CDMA communication system.

Although not shown in FIG. 3, another JACK channel can be supported in aforward link 40 to support sporadic messages generated in a forward linkdirection to a particular subscriber unit 14.

As previously discussed, wireless communication system 10 can supportshort duration, high-speed data bursts on forward link channels from oneor multiple base stations 20 to subscriber units 14. In one application,the data information transmitted over the forward link 40 includesdigitally encoded data blocks 205 such as web page information to PCdevice 12. In this instance, the JACK channel 54 is used to carryacknowledgment messages to indicate receipt of the web page information.

A network session can be established by sending a SYN message from PCdevice 12 to server 30. This is typically how a session is establishedbetween a client such as PC device 12 requesting web page informationand a server 30 providing the web page information. In response toreceipt of a SYN message at server 30, an ACK message is thereaftergenerated and transmitted from server 30 to corresponding PC device 12to indicate that the SYN messages was received by server 30. Infurtherance of the TCP/IP protocol, the PC device 12 after receiving theACK would then send a return ACK message to server 30 indicating thatthe ACK was received. Consequently, a network session is established totransmit data such as web page information from server 30 tocorresponding PC device 12.

As previously discussed, web page information is then transmitted fromserver 30 over assigned forward link traffic channels 42. A portion ofJACK channel 54 is allocated for use by the corresponding subscriberunit 14 to transmit, for example, sporadically generated ACK messages inthe reverse link 50 direction to server 30. As is known, thesesubsequent and sporadically generated ACK messages transmitted by thesubscriber unit 14 are used to acknowledge receipt of data informationat subscriber unit 14 or PC device 12 for a particular establishednetwork session.

JACK channel 54 is preferably structured as multiple periodicallyrepeating time-slots 310, each of which is used to transmit 64 bits ofinformation encoded via symbols from a subscriber unit 14 to the basestation 20. Each subscriber unit 14 preferably synchronizes itself withbase station 20 based on a forward link channel so that a subscriberunit 14 can properly transmit data in an assigned time slot 310. Precisesynchronization with base station 20 ensures that the subscriber units14 do not interfere with each other while transmitting in adjacent timeslots 310 on the reverse direction JACK channel 54.

Combined, the total duration of one cycle of time slots 0 . . . F is26.6 mS for encoding 1024 bits of data information. One cycle ofperiodically repeating time slots 310 is also known as an epoch 315 oftime duration, T. Of course, a duration of a time slot 310 and number ofbits encoded in a time slot 310 can be adjusted to suit a particularapplication.

In an illustrative application where system 10 supports wireless CDMAcommunications, JACK channel 54 is modulated via BPSK (Binary PhaseShift Keying) and framed with a ½ rate FEC (Formal Error Correction)code. As mentioned, appropriate equipment at base station 20 is used toreceive messages encoded in each of the multiple time slots 310. Ofcourse, JACK channel 54 can be modulated and FEC coded at differentrates. For example, different FEC codes can be used for transmission ofinformation in different time slots 310. Likewise, communication system10 is optionally implemented so that subscriber units 14 each cantransmit messages in a time slot 310 based on a different or assignedmodulation rate.

The shared JACK channel 54 is optionally structured so that bits in atime slot 310 have a specified meaning. More specifically, certain bitssuch as bit 4 and bit 5 in a time slot 310 of the shared JACK channel 54as set by a subscriber unit 14 can be used to communicate a particularmessage to base station 20. For instance, a single bit such as ACK/NAKbit 341 (bit 4) that is transmitted in a time slot 310 can be used totransmit a message to the base station 20 regarding a particular networksession, where the setting of the bit itself indicates a message-type.

In an application where the single bit is an ACK/NAK bit 341(Acknowledgment/No Acknowledgment bit), a logic one can indicate that amessage is an “acknowledgment” message while a logic zero can indicatethat a message is a “no acknowledgment” message. Thus, a base station 20transmitting information over a forward link 40 channel to a subscriberunit 14 can be provided feedback in a reverse link 50 via messagestransmitted on the JACK channel 54.

In certain applications, the messages transmitted in a time slot 310 ofthe JACK channel 54 can be considered substitute messages in somerespects because an ‘ACK’ message, e.g., self-contained network packetas originally transmitted by a PC device 12, is optionally interceptedand converted by a subscriber unit 14 into a newly encoded message thatis transmitted in a time slot 310 of the JACK channel 54.

In an application where a specific message is not transmitted in everytime slot 310 from the subscriber unit 14 to the base station 20, i.e.,an acknowledgment message is not sent every periodically repeating timeslot 310, a complementary data valid bit 342 (bit 5) can be transmittedin a time slot 310 to indicate that the setting of a correspondingACK/NAK bit 341 is meaningless. For example, a complementary data validbit 342 such as bit 5 can be set as a logic one or zero to indicate thatthe ACK/NAK bit 341 is valid or otherwise invalid, respectively. In thisway, two bits such as bits 4 and 5 of a time slot 310 can be used tocommunicate a particular message to the base station 20. When thecomplementary data valid bit 342 is a logic zero, the setting of theACK/NAK bit 341 is meaningless. Thus, no message is being sent at leastfor that particular time slot 310. Accordingly, it is possible for anassigned subscriber unit 14 not to transmit a message to the basestation 20 every successive periodically repeating time slot 310 of theshared reverse link JACK channel 54.

Based on this method, a message that would otherwise be transmittedalong with other data payload messages on a reverse link traffic channel52 can be converted and transmitted as a substitute message using one ortwo bits in a time slot 310 of the shared reverse link JACK channel 54.This aspect of the present invention is particularly advantageous inapplications where limited resources are available for transmitting datainformation in a reverse link channel because a message can betransmitted using fewer bits. More specifically, a self-containedswitched network packet that would otherwise include many more bits toencode an acknowledgment message is substantially reduced in size andtransmitted as a substitute message in a time slot 310 of the JACKchannel 54.

In one application, the L4 (layer 4) indicator bit pair 340 aspreviously described is used to encode layer 4 ACK messages for aparticular network session between PC device 12 and server 30. Notably,certain fields of a time slot 310 in addition to the L4 indicator bitpair 340 as described above can be allocated for encoding additionaldetails of a corresponding layer 4 acknowledgment message. For example,16 bits of a time slot 310 can be allocated to encode an L4 streamidentification tag 344 identifying an established session fortransmitting data between a PC device 12 and server 30. Another 16 bitsof a time slot 310 can be allocated to encode an L4 stream value tag 34identifying a network packet number being identified for the establishedsession between subscriber unit 14 and server 30. Based on data in thesefields of a time slot 310, a self-contained layer 4 ACK-type messagegenerated by PC device 12 can be properly encoded and transmitted in atime slot 310 of JACK channel 54 to server 30 via a wireless linkthrough base station 20. According to one aspect of the presentinvention, a self-contained switched network message as originallytransmitted by PC device 12 is reconstructed at base station 20 based onthe L4 acknowledgment data information in a time slot 310 of JACKchannel 54. The ACK network message reconstructed at the base station 20is then further transmitted over network 24 to target server 30.

FIG. 7 is a block diagram illustrating the generation of a networkpacket and how it is transformed into a substitute message according tothe principle of the present invention. Message A including an Ethernetheader is generated at, for example, PC device 12-1 and is bound forserver 30 through JACK 54. As shown, Message A is transformed into asubstitute message A′ at subscriber unit 14-1 and is transmitted in acorresponding time slot 310 of JACK channel 54 channel. Message A′received at base station 20 in a time slot 310 is then reconstructedinto a switched network packet message A″ including an appropriateEthernet header and is transmitted to server 30 in a substantiallysimilar form as originally generated by PC device 12-1. In this way, anetwork message is efficiently forwarded over communication system 10and the wireless link between subscriber unit 14 and base station 20does not otherwise act as a bottleneck that inhibits data transfers.

Referring again to FIG. 3, the L4 stream ID (Identification) tag 344 ispreferably a 16-bit number that identifies a particular L4 sessionbetween a PC device 12 and server 30 based on source/destination IP(Internet Protocol) address and source/destination port numbers. Inother words, a source IP address (32 bits), destination IP address (32bits), source port number (16 bits) and destination port number (16bits) are hashed or reduced into a 16-bit L4 stream ID number thatidentifies a particular session. Both the subscriber unit 14 and basestation 20 will track a session based on this 16-bit L4 stream ID tag344. Accordingly, up to 65,534 individual sessions can be supported viathis method of identifying a session type based on the 16-bit L4 streamID tag 344. This excludes a use of 0000 hex and FFFF hex as L4 stream IDtags since they are reserved for special use.

When a session is established between PC device 12 and server 30, basestation 20 and subscriber units 14 each track the new session based onthe 16-bit L4 stream identifier tag 344. In one application, each newsession is assigned a stream identifier tag 344 based on a one-upcounter. For example, based on the detection of a new sessionestablished transmission between PC device 12 and server 30, a sessionis assigned a next available tag number at base station 20. A message isthen transmitted to the subscriber unit to which session the newlyassigned 4 stream identifier tag 344 pertains. In this way, both thebase station 20 and subscriber unit 14 simultaneously track each sessionbased on the 16-bit L4 stream identifier tag 344. Each newly detectedand established session would be assigned a new L4 stream ID Tag 344such as 0001 hex, 0002 hex, 0003 hex and so on as they are established.

Based on this method, a subscriber unit 14 intercepting an L4 ACKmessage generated by a corresponding PC device 12 identifies the sessionnumber to the base station 20 associated with the L4 ACK message basedupon the source/destination IP address and source/destination portnumbers. For instance, the 16-bit L4 stream ID tag 344 corresponding tothe session is transmitted in a time-slot 310 in lieu of 96 bits ofsource/destination IP address and source/destination port numbers toidentify the session to which the ACK message pertains. This aspect ofthe present invention is advantageous because 16 bits rather than 96bits are used to identify a particular network session.

FIG. 6 is a table illustrating the Layer 4 stream ID tag 344 andcorresponding session information that is tracked at both the basestation 20 and subscriber unit 14 for a particular link between PCdevice 12 and server 30. As mentioned, subscriber unit 14 intercepts anL4 ACK message and notifies base station 20 of the session to which themessage corresponds based on the L4 stream ID tag 344. Base station 20can then reconstruct the originally transmitted L4 ACK message into aself-contained switched-network packet that is forwarded to server 30based upon the corresponding source/destination IP address andsource/destination port number as retrieved from the table. Morespecifically, base station 20 identifies the source/destination IPaddress and source/destination port numbers for an L4 ACK messagereceived in a time slot 310 based upon entry in the table andreconstructs and forwards the network message accordingly.

Referring again to FIG. 3, the L4 stream value tag 346 is a 16-bitnumber identifying the position in the octet stream of the Layer 4session that is being acknowledged by PC device 12. Thus, PC device 12can acknowledge receipt of network packets according to the TCP/IPprotocol based on network messages transmitted in the reverse link JACKchannel 54. For example, the ACK message including the L4 stream valuetag 346 can identify the number of messages properly received at PCdevice 12.

The L3 indicator bit pair 330 is similar to the L4 indicator bit pair340 except the L3 indicator bit pair 330 is dedicated for layer 3message processing. In a preferred embodiment, layer 3 messageprocessing is used to verify that a data block 205 or superframe isproperly received at a corresponding subscriber unit 14. In addition tothe L3 indicator bit pair 330, Layer 3 ACK/NAK messages as transmittedin a time slot 310 over JACK channel 54 can include additional bitsidentifying the L3 superframe that is being acknowledged.

A superframe can be a data block 205 such as a TCP/IP network messagethat is reduced into segments or sub-blocks prior to transmission overforward link traffic channels to corresponding PC device 12 throughsubscriber unit 14. Each segment of a superframe or data block 205 ispreferably sized so that it can be transmitted in a frame of the forwardlink 40 channel. When received at a corresponding subscriber unit 14,the segments are reassembled to form recaptured data block 255. Therecaptured data block 255 or original network message is then forwardedto, for example, a target PC device 12 coupled to the subscriber unit14. Meanwhile, an acknowledgment message is generated at the subscriberunit 14 for transmission to the base station 20 in the appropriate timeslot 310 of the JACK channel 54 to acknowledge receipt of the receivedsuperframe. The superframe ID number 335 in a time slot 310 indicatesthe superframe or data block 205 being acknowledged by subscriber unit14. Each superframe is sequentially numbered so that it can identifiedaccordingly. Preferably, a 5-bit field is allocated for the superframeID number 335 in a time slot 310.

The L2 indicator bit pair 320 is similar to the L4 indicator bit pair340 except the L2 bit pair is instead dedicated to layer 2 messageprocessing. Layer 2l processing assures that specific frames or segmentsof data information are properly received at a corresponding subscriberunit 14. As previously discussed, a frame is a block, sub-block orsegment of a superframe of data transmitted over the forward link 40 tothe subscriber unit 14. If a frame is not properly received due to datacorruption caused by channel interference, the base station 20 must benotified so that the frame can be re-transmitted to the subscriber unit14. According to the principles of the present invention, feedbackmessages in the appropriate time slot 310 of the JACK channel 54 promptbase station 20 to re-transmit an old frame of data or transmit a newframe of data.

The L2 frame ID tag 325 preferably identifies the frame number that isbeing acknowledged. For example, base station 20 initially transmits aspecified frame number such as frame #0 to subscriber unit 14. Thesubscriber unit 14 will then need time to demodulate the received framedata and decode the symbols based of the FEC code. In the meantime,additional sequentially numbered frames of data information such asframes 1, 2, 3 . . . are transmitted by base station 20 and received ata corresponding subscriber unit 14. The acknowledgment messagetransmitted in the reverse link JACK channel 54 indicates to the basestation 20 whether a corresponding frame such as frame #0 should beresent. Notably, frame numbers for L2 frame ID tag 325 roll over toframe #0 again after frame #7 is sent to a particular subscriber unit14.

Preferably, the L2 frame ID tag 325 includes multiple bits so thatmultiple frames can be identified in the process oftransmitting/receiving frame data. For example, one frame ID tag canidentify a frame being transmitted to a subscriber unit 14 while anotherframe ID tag can identify a received frame being processed at asubscriber unit 14.

Each time-slotted message 310 optionally includes a CRC (CyclicalRedundancy Check) packet 360 that is used for error-checking purposes.Based on a received CRC packet 360, the base station 20 can determinewhether the 64 bits of data received in a particular time slot 310 hasbeen corrupted during transmission. Reserved bits 350 in a time slot 310are provided for the future growth.

If no forward link channels are assigned for use by a particular fieldunit and no time slots are available for allocation in the sharedreverse link channel, information can be transmitted from the field unitto the base station via the assignment of reverse link traffic channels.

As previously discussed, the shared channel can be structured to encodenetwork messages generated at different layers. Alternately, the sharedchannel can be an unstructured channel partitioned into time slots thatcarry generic payload data. For example, a network message or raw datacan be encoded in a time slot of a shared channel where a receiverdevice must decode a data payload to determine a message type. Thus, theshared channel can carry any type of message and not just acknowledgmentor feedback messages. For instance, a data payload transmitted in a timeslot of the shared channel can be a maintenance message to support acorresponding link between the field unit and base station. Otherwise,such data can be transmitted over a traffic channel.

Another aspect of the present invention involves allocating additionalbandwidth such as a reverse link traffic channel for transmitting a datamessage to the base station when throughput capacity afforded by anassigned time slot is exceeded. That is, if a field unit must transmitmore information to the base station than is possible via an assignedtime slot, at least part of a reverse link traffic channel isadditionally assigned for use by the field to transmit information tothe base station.

FIG. 4 is a timing diagram illustrating the delays associated with thegeneration and transmission of a feedback message in the shared reverselink JACK channel 54. Generally, one or multiple forward trafficchannels 42 are assigned for use by a particular subscriber unit 14 instep 410. A message indicating this new traffic channel assignment istransmitted by base station 20 to the corresponding subscriber unit 14.In following step 415, the subscriber unit 14 decodes the message todetermine this new assignment of forward link 40 channels.

Based on this new assignment of traffic channels 42, the base station 20transmits data information to the corresponding subscriber unit 14 instep 420. The subscriber unit then demodulates and decodes the receivedpayload message in step 425 and, in a following step 430, transmits anACK message over the appropriate JACK channel 54 time slot 310 toindicate whether the data is properly received. In step 435, basestation 20 demodulates and decodes the ACK message received from thesubscriber unit 14 in a corresponding time slot 310.

FIG. 5 is a JACK channel time slot assignment chart that is preferablymaintained at both the base station 20 and subscriber unit 14. Table 500illustrates JACK channel time slot usage for up to 4 epoch offsets.Table 500 is useful because it ensures that a subscriber unit 14transmits a time-slotted message in the appropriate epoch and that basestation 20 can identify to which forward link transfers the reverse linkmessage pertains based upon a particular Epoch that is being processed.Accordingly, the subscriber units 14 can send a feedback message ofpreviously received data information in the appropriate time slots 310at a future point in time based on entries in the time slot assignmentchart.

In one embodiment, table 500 at the base station 20 includes entries ineach cell 510 indicating an ID Tag of a subscriber unit 14 that isallowed to transmit information during a given time slot 310. The table500 maintained at the subscriber unit 14 includes a flag in each cell510 indicating which time slots 310 have been assigned for its use.Thus, subscriber unit 14 can determine in which time slot 310 totransmit a corresponding message and base station 20 can identify fromwhich subscriber unit 14 a message pertains.

In a preferred embodiment, time-slots 310 are implicitly assigned foruse by subscriber unit 310 based on the allocation of forward linktraffic channels 42. For example, a subscriber unit 310 is allocated useof a time slot 310 in the reverse link JACK channel 54 depending onwhich traffic channels 42 are used in the forward link 40 to transmit adata payload to the subscriber unit 14. More specifically, if the basestation 20 transmits forward link messages on traffic channel #1, timeslot #1 of the shared reverse link channel in a delayed Epoch isimplicitly assigned for use by that particular subscriber unit 14 totransmit feedback information in a reverse link path of the JACK channel54. Transmission of a message in a particular time slot 310 by a newlyassigned subscriber unit 14, as mentioned, is delayed so that thesubscriber unit 14 can receive and process data received on the newlyassigned forward link channel 40 and respond appropriately in thereverse link time slot 310 of JACK channel 54. When utilized, thisaspect of the present invention alleviates the need to transmit explicitmessages from the base station 20 to subscriber units 14 indicatingwhich time slot 310 is to be used for data messages.

Notably, a subscriber unit 14 can receive data information from the basestation 20 on multiple forward link traffic channels 42 while providingcorresponding feedback messages on multiple implicitly assigned timeslots of the shared JACK channel 54.

In an alternate embodiment, one or multiple time slots 310 areexplicitly assigned for use by a subscriber unit 14 via a correspondingmessage sent on a forward link channel 40 from the base station 20 to asubscriber unit 14 indicating which of multiple time slots will beassigned for use in the reverse link JACK channel 54 to carry feedbackmessages.

FIGS. 8-19 are flow charts based on SDL (Specification and DescriptionLanguage) as promulgated by the ITU (International TelecommunicationUnion) specification z.100.

FIG. 8 is a flow chart illustrating the assignment of JACK channel usageaccording to the principles of the present invention. Step 810illustrates entry point of the subroutine as shown. In step 820, theresource manager in the base station 20 indicates that a particularforward traffic channel (FTCH) is assigned for use by a subscriber unit14 and corresponding PC device 12. Based on this assignment of forwardtraffic channel, it is noted in which Epochs the traffic channels areassigned in step 830. Following in step 840, the subscriber unit 14identification number is stored in the appropriate Epoch entries of theJACK receive table of FIG. 5. Finally, confirmation of the assignedtraffic channel is sent to the resource manager of base station 20 instep 850.

FIG. 9 is a flow chart illustrating JACK channel processing at the basestation according to the principles of the present invention. Step 910shows the entry point into the subroutine. In step 915, an indication isreceived that the information for a particular Epoch, i.e., time slots0-N, have been demodulated, decoded and the corresponding information isready for further processing by the base station 20. The index counter,N, is set to zero in step 920 for processing data received in a timeslot 310. Following in step 925, the information in a time slot N isprocessed. Step 925 is itself a subroutine as shown in FIG. 10. Step 930and step 935 are part of a “for next” loop so that all time slots areappropriately processed. JACK receive table rows are then moved up instep 940 for processing in the following Epoch. Step 950 shows the endof this subroutine.

FIG. 10 is a flow chart illustrating more specific details of JACKchannel time slot 310 processing according to the principles of thepresent invention. Step 1010 is an entry point into the subroutine. Instep 1015, the subscriber unit ID corresponding to the time slot 310 isretrieved to identify from which subscriber unit 14 a message isreceived. Following in step 1020, it is determined whether an L2 ACK isencoded in the bits of a time slot. If so, the L2 ACK bits are processedaccordingly in step 1025. Thereafter, it is determined in step 1030whether an L3 ACK is encoded in the bits received in a particular timeslot 310. If so, the L3 ACK bits are processed in step 1035. Finally, itis determined in step 1040 whether an L4 ACK is encoded in the bitsreceived in a particular time slot 310. If so, the L4 ACK bits areprocessed accordingly in step 1045. After processing of layers, thesubroutine ends in step 1050.

FIG. 11 is a flow chart illustrating how a session is tracked andidentified for a link between a PC device 12 and server 30 according tothe principles of the present invention. Step 1110 is an entry pointinto subroutine as shown. In step 1115, an L4 stream or session betweena PC device 12 and a server 30 is identified at the base station 20. AnL4 stream ID tag 344 is then assigned in step 1120 to the particularsession based on a one-up counter. This information is stored in thetable FIG. 6 to track established TCP sessions. Following in step 1125,a message is sent from the base station 20 to the correspondingsubscriber unit 14 to indicate the L4 stream ID tag 344 that will beused to track a particular network session. The 32-bitsource/destination address and 16-bit source/destination port number ofthe session are preferably sent to the corresponding subscriber unit 14so that their tables match for tracking such sessions. Step 1130 showsthe end of the subroutine.

FIG. 13 is a flow chart illustrating the acknowledgment of a sessionidentification tag at a subscriber unit according to the principles ofthe present invention. Step 1310 shows the entry point of thesubroutine. In step 1315, the stream sync message as recently discussedfor the flow chart of FIG. 11 is received at the subscriber unit 14. Itis then determined whether the message is properly received in step1320. If not, a negative acknowledgment is generated and transmitted tothe base station 20 in step 1335 indicating that the message was notproperly received and the table maintained at the subscriber unit 14cannot be properly updated. If stream sync message is properly receivedin step 1320, the stream ID and related information in mapping table ofFIG. 6 is updated at the subscriber unit 14 to track a particularsession in step 1325. Thereafter, an acknowledgment message regardingthe update is sent to the base station 20 in step 1330. Step 1340 showsthe end of subroutine.

FIG. 12 is a flow chart illustrating the acknowledgment of a session tagreceipt at a subscriber unit according to the principles of the presentinvention. Step 1210 shows the entry point of the subroutine. In step1215, the stream sync ACK message as generated by the subscriber unit 14in the flow chart of FIG. 13 is received for further processing at basestation 20. It is then determined in step 1220 whether the subscriberunit properly acknowledges the newly established session based on themessage sent to the subscriber unit 14 as discussed in FIG. 11. If so,the L4 stream ID mapping at the base unit is updated in step 1225 totrack a particular network session as shown in FIG. 6. If not, thenegative ACK in step 1230 indicates that the JACK channel is notavailable for transmitting data. Step 1235 illustrates the end of thissubroutine.

FIG. 14 is a flow chart illustrating JACK channel time slot assignmentat a subscriber unit according to the principles of the presentinvention. Step 1410 illustrates the entry point into this subroutine.In step 1415, the subscriber unit 14 receives notification that aforward traffic channel has been assigned for its use. It is thendetermined in step 1420 in which epoch the particular subscriber unit 14will transmit information to the base station 20 over a time slot 310 ofthe JACK channel 54. As previously discussed, the subscriber unit 14will transmit an acknowledgment in the JACK channel 54 after a delay ofone or more Epochs for a message received in an assigned forward trafficchannel. The JACK transmit table is then marked with a flag in step 1425to indicate in which Epoch and time slot 310 a subscriber unit 14 is toreply for received messages. Step 1430 shows the end of this subroutine.

FIG. 15 is a flow chart illustrating the generation of an L2 ACK at asubscriber unit according to the principles of the present invention.Step 1510 illustrates an entry point of the subroutine. In step 1515, anindication is received that messages as received on the forward trafficchannel at the subscriber unit have been demodulated and decoded for aparticular frame includes L2 ACK information. In step 1520, it isdetermined that L2 ACK message will be sent and the data ready bit forthe L2 ACK message is set high indicating that an L2 message is beingtransmitted in a particular time slot 310. It is then determined in step1525 whether a previous frame of data was properly received at thesubscriber unit 14 on the forward link traffic channel. For example,there could be a CRC or other type of error indicating non-receipt offrame data. If a frame is properly received, the ACK bit is setindicating such a condition in step 1530. If not, the appropriate bit ofthe time slot 310 is reset indicating the frame receive error in step1535. Finally in step 1540, the L2 frame ID tag 325 is encoded in thetime slot 310 for the frame number being acknowledged. Step 1545 is theend of this subroutine.

FIG. 16 is a flow chart illustrating the generation of an L3 ACK at asubscriber unit according to the principles of the present invention.Step 1610 illustrates an entry point of the subroutine. In step 1620, anindication is received that messages received on the forward trafficchannel at the subscriber unit have been demodulated and decoded for aparticular superframe. The data ready bit for the L3 ACK message is sethigh indicating that an L3 message is being transmitted for a particulartime slot 310. It is then determined in step 1640 whether a superframeof data was properly received at the subscriber unit 14 on the forwardlink traffic channel. For example, there could be a CRC or other type oferror indicating non receipt of data. If a superframe is properlyreceived as determined in step 1640, the ACK bit of the time slot 310 isset indicating so in step 1650. If not, the appropriate bit of the timeslot 310 is reset indicating the superframe receive error in step 1660.Finally in step 1670, the L3 superframe ID tag 325 is encoded in thetime slot 310 for the superframe being acknowledged. Step 1680 is theend of this subroutine.

FIG. 17 is a flow chart illustrating the generation of an L4 ACK at asubscriber unit according to the principles of the present invention.Step 1710 illustrates an entry point of the subroutine. In step 1715, anL4 ACK message bound for server 30 as generated by PC device 12 isintercepted at a particular subscriber unit 14. The data ready bit forthe L4 ACK message is set high in step 1720 indicating that an L4message is being transmitted in a particular time slot 310. It is thendetermined in step 1725 whether the intercepted L4 ACK message wasproperly received at the subscriber unit 14 from the PC device 12 andthat the ACK message should be transmitted over the JACK channel 54. Ifthe L4 ACK should be transmitted in the JACK Channel 54 as determined instep 1725, the L4 ACK bit is set indicating so in step 1730. If not, theappropriate bit of the time slot 310 is reset in step 1735 indicatingthat a no acknowledgment is being sent to base station 20. Finally instep 1740, the L4 stream value 346 and stream identifier tag 344 areencoded in the time slot 310. Step 1745 indicates the end of thissubroutine.

FIG. 18 is a flow chart illustrating how a TCP acknowledgment messagesis intercepted and encoded in a time slot according to the principles ofthe present invention. Step 1810 illustrates an entry point in to thissubroutine. In step 1815, a TCP acknowledgment message as generated byPC device 12 is intercepted at subscriber unit 14. It is then determinedwhether a time slot 310 of the JACK channel 54 has been assigned for usein step 1820. If not, the acknowledgment or other message is transmittedto the base station 20 over another reverse traffic channel in step1845. If a JACK channel 54 time slot 310 is assigned for use by asubscriber unit 14 as determined in step 1820, the source/destinationaddress and source/destination port number is extracted from the L4 ACKmessage received from PC device 12 in step 1825. Following step 1830,the corresponding session to which the network packet pertains islocated in the table of FIG. 6. If the layer 4 stream ID tag 344corresponding to a particular session is not found in step 1840, themessage is transmitted over a reverse link traffic channel in step 1845.On the other hand, if the layer 4 stream ID tag 344 is identified instep 1840, this ID tag 344 is encoded for transmission in theappropriate time slot 310 for the particular acknowledgment message instep 1850. Also, in step 1850, the L4 stream value 346 in the time slot310 is encoded based upon the TCP header field acknowledgment number ofthe network L4 ACK message. Step 1860 indicates the end of thissubroutine.

FIG. 19 is a flow chart illustrating how a layer 4 ACK message asencoded in a time slot is reconstructed and transmitted to a targetnetwork device such as server 30 according to the principles of thepresent invention. Step 1910 illustrates an entry point for thesubroutine. Based upon the receipt of the layer 4 bit information in atime slot 310 at the base station 20 and, more specifically, the L4stream ID tag 344, the session corresponding to the stream ID is locatedin the table of FIG. 6 in step 1915. If an entry is not found in step1920 for the session, it is presumed the subscriber unit 14 is no longersynchronized with the base station 20 as shown in step 1925.Alternatively, if an entry is found in step 1920, the source/destinationaddress and source/destination port number associated with the ACKmessage is extracted from the table in step 1930. A switched networkpacket is then reconstructed in step 1935 to include the parameters ofthe L4 ACK message as originally intercepted at subscriber unit beforeit was transmitted over the time slot 310 of the JACK channel 54. Thus,the substitute message as received in a time slot 310 of the JACKchannel 54 is converted into a message that is forwarded over a networkto a target device in step 1940. Step 1945 illustrates the end of thesubroutine.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

What is claimed is:
 1. A method implemented by a subscriber unit in awireless communication, wherein the method comprises: intercepting anacknowledgment message for transmission to a base station with payloaddata; converting the acknowledgment message into a substitute message ofacknowledgement, the substitute message to be transmitted to the basestation without the payload data; encoding the substitute message into anewly encoded message of acknowledgment for transmission on a sharedreverse link channel to a base station without the payload data; andtransmitting acknowledgment information associated with a receivedsession tag at the subscriber unit to the base station over the sharedreverse link channel via the newly encoded message of acknowledgment, ona condition that the session tag is received from a network server viathe base station on a forward link channel and identified by thesubscriber unit.
 2. The method as in claim 1, wherein the shared reverselink channel is divided into multiple time slots and the subscriber unitis assigned at least one time slot for transmitting the acknowledgementinformation.
 3. The method as in claim 2, wherein use of an assignedtime slot for transmitting messages in a reverse direction is delayed apreselected amount of time after a traffic channel is allocated fortransmitting a data payload.
 4. The method as in claim 3 furthercomprising: allocating additional bandwidth to a subscriber unit fortransmitting acknowledgment information when throughput capacityafforded by a single time slot is exceeded.
 5. The method as in claim 4,wherein the additional bandwidth is at least part of a traffic channel.6. The method as in claim 3, wherein the data payload includes at leastone network message transmitted between processing devices using anetwork protocol.
 7. The method as in claim further comprising the stepof: synchronizing the acknowledgment channel with another channel in aforward or a reverse channel so that acknowledgment information istransmitted or received in a corresponding time slot.
 8. The method asin claim 2, wherein the time slot includes CRC (Cyclical RedundancyCheck) bits.
 9. The method as in claim 2, wherein acknowledgmentinformation is transmitted in at least two time slots from at least twodifferent subscriber units.
 10. The method as in claim 2, wherein a timeslot is implicitly assigned for use by the subscriber unit based upon anassignment of a corresponding channel for transmitting a data payloadfrom the base station to the subscriber unit.
 11. The method as in claim1, wherein the acknowledgment information is transmitted on an as-neededbasis between the base station and the subscriber unit.
 12. The methodas in claim 1, wherein a plurality of subscriber units are allocatedmultiple forward link channels on an as-needed basis to transmit a datapayload from the base station to the plurality of subscriber units and aportion of the acknowledgment channel in a reverse link carries feedbackmessages to the base station.
 13. The method as in claim 1, wherein afirst acknowledgment channel is allocated for use in a forward link anda second acknowledgment channel is allocated for use in a reverse linkof the wireless communication.
 14. The method as in claim 1, wherein theacknowledgment information indicates that a data payload was properlyreceived.
 15. The method as in claim 1, wherein the acknowledgmentinformation indicates that a data payload was not properly received. 16.The method as in claim 1, wherein the wireless communication includes atleast one network message based on TCP/IP (Transmission Control ProtocolInternet Protocol).
 17. The method as in claim 1, wherein the sessionincludes a layer 4 stream between a processing device and the networkserver via the subscriber unit coupled to the processing device and viathe base station coupled to the network server.
 18. The method as inclaim 17: wherein the layer 4 stream of the session comprises an L4(layer 4) indicator bit pair; and wherein the method further comprises:encoding layer 4 ACK messages for a particular network session via theL4 indicator bit pair.
 19. The method as in claim 17, wherein the methodfurther comprises: receiving layer 4 bit information in a time slot ofthe shared reverse link channel; searching for an L4 stream ID tag in atable to determine whether or not the subscriber unit is synchronizedwith the base station; and wherein the subscriber unit is determined tono loner be synchronized with the base station when the L4 stream ID tagis not found in the table.
 20. The method as in claim 1: wherein thesubstitute message has one to two bits of data in a time slotidentifying a selected message type for the substitute message; andwherein the selected message type is transmitted using fewer bits thanif the message prior to conversion were transmitted over a communicationlink along with a set of random data packets which are required to bedecoded to determine their content.
 21. The method as in claim 1,further comprising: notifying the base station of which network sessionthe newly encoded message of acknowledgment corresponds based on thesession tag received; wherein the session tag received comprises an L4(layer 4) stream ID tag from which the base station is to reconstructthe originally transmitted and intercepted acknowledgment message into aself-contained network packet as originally transmitted prior to beingintercepted.
 22. A subscriber unit in a wireless communication, thesubscriber unit comprising: the subscriber unit to intercept anacknowledgment message for transmission to a base station with payloaddata; the subscriber unit to convert the acknowledgment message into asubstitute message of acknowledgement, the substitute message to betransmitted to the base station without the payload data; an encoder ofthe subscriber unit to encode the substitute message into a newlyencoded message of acknowledgment for transmission on a shared reverselink channel to a base station without the payload data; and atransmitter of the subscriber unit to transmit acknowledgmentinformation associated with a received session tag at the subscriberunit to the base station over the shared reverse link channel via thenewly encoded message of acknowledgment, on a condition that the sessiontag is received from a network server via the base station on a forwardlink channel and identified by the subscriber unit.